Ganglionated plexi and ligament of Marshall ablation reduces atrial vulnerability and causes stellate ganglion remodeling in ambulatory dogs

Abstract

Background: Simultaneous activation of the stellate ganglion (SG), the ligament of Marshall (LOM), and the ganglionated plexi often precedes the onset of paroxysmal atrial tachyarrhythmia (PAT).

Objective: The purpose of this study was to test the hypothesis that ablation of the LOM and the superior left ganglionated plexi (SLGP) reduces atrial vulnerability and results in remodeling of the SG.

Methods: Nerve activity was correlated to PAT and ventricular rate (VR) at baseline, after ablation of the LOM and SLGP, and after atrial fibrillation. Neuronal cell death was assessed with tyrosine hydroxylase and terminal deoxynucleotidyl transferase dUTP nick end label (TUNEL) staining.

Results: There were 4 ± 2 PAT episodes per day in controls. None were observed in the ablation group, even though SG nerve activity and VR increased from 2.2 µV (95% confidence interval [CI] 1.2-3.3 µV) and 80 bpm (95% CI 68-92 bpm) at baseline, to 3.0 µV (95% CI 2.6-3.4 µV, P = .046) and 90 bpm (95% CI 75-108 bpm, P = .026) after ablation, and to 3.1 µV (95% CI 1.7-4.5 µV, P = .116) and 95 bpm (95% CI 79-110 bpm, P = .075) after atrial fibrillation. There was an increase in tyrosine hydroxylase-negative cells in the ablation group and 19.7% (95% CI 8.6%-30.8%) TUNEL-positive staining in both the left and right SG. None were observed in the control group.

Conclusion: LOM and SLGP ablation caused left SG remodeling and cell death. There was reduced correlation of the VR response and PAT to SG nerve activity. These findings support the importance of SLGP and LOM in atrial arrhythmogenesis.

Keywords: Ablation; Atrial fibrillation; Ligament of Marshall; Superior left ganglion plexi.

Figure 1. Ablation of the SLGP and LOM and the study protocol

A, Ligament of Marshall (LOM, black arrowhead) and superior left ganglionated plexi (SLGP, white arrowhead). B, The scar after SLGP ablation (black arrowhead). C, Diagram of study protocol.

Figure 2. Stellate ganglion nerve activity (SGNA) and ventricular rate (VR)

A was recorded at baseline. The onset of SGNA (red bar) was identified first, then the average VR 5 seconds prior to and 5 seconds after the onset of SGNA was determined. B, The same analyses was performed to compare the occurrence of SGNA to VR at baseline post-ablation. An example showing SGNA that induced little VR change is shown.

Figure 3. Effect of SLGP and LOM ablation on SGNA-induced VR changes

A, Statistical dot plot showing that the SGNA-induced VR acceleration was markedly attenuated by SLGP ablation compared with the control group. B, An example at baseline shows that a burst of SGNA led to VR increase from 67 to 117 bpm (74.6% increment). C, An example after SLGP ablation shows that a burst of SGNA led to VR increase from 62 to 73 bpm (17.7% increment).

Figure 4. The episodes of paroxysmal atrial tachyarrhythmia (PAT) and paroxysmal atrial fibrillation (PAF)

A, An example of PAT; B, 4 continuous PAT episodes within 90 seconds; C, An example of PAF.

Figure 5. Tyrosine hydroxylase (TH) staining of the SG

Low magnification (1.25X objective lens) shows the presence of both a damaged region and a normal region in the same LSG (Panel A) and RSG (Panel B) of the ablation group. Images of these regions are also shown under a higher magnification (20X objective lens). Arrows point to ganglion cells that did not stain for tyrosine hydroxylase (TH negative). There was evidence of nuclear shrinking and pyknosis in the ganglion cells; Panels C and D show the control group LSG and RSG respectively.

Figure 6. Confocal images of TH and TUNEL double staining of SG

Green shows positive TUNEL stain, red indicates the positive TH stain and blue is the DAPI stain of the nuclei. There were 2 patterns observed in the SG of the GP ablation group. In the first pattern, LSG (A) have TUNEL-positive ganglion cells, and occasional TUNEL-positive ganglion cells were found in RSG (B). In the second pattern, both LSG (C) and RSG (D) have the same percentage of TUNEL-positive ganglion cells. There were no TUNEL-positive cells in the LSG (E) or RSG (F) of the control group.